189981901 has 2 divisors, whose sum is σ = 189981902. Its totient is φ = 189981900.

The previous prime is 189981899. The next prime is 189981907. The reversal of 189981901 is 109189981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 135606025 + 54375876 = 11645^2 + 7374^2 .

It is an emirp because it is prime and its reverse (109189981) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 106186681 and 186681601.

It is a cyclic number.

It is not a de Polignac number, because 189981901 - 2¹ = 189981899 is a prime.

Together with 189981899, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (189981907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94990950 + 94990951.

It is an arithmetic number, because the mean of its divisors is an integer number (94990951).

Almost surely, 2^189981901 is an apocalyptic number.

It is an amenable number.

189981901 is a deficient number, since it is larger than the sum of its proper divisors (1).

189981901 is an equidigital number, since it uses as much as digits as its factorization.

189981901 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 46656, while the sum is 46.

The square root of 189981901 is about 13783.3922167223. The cubic root of 189981901 is about 574.8714530537.

The spelling of 189981901 in words is "one hundred eighty-nine million, nine hundred eighty-one thousand, nine hundred one".